Syneresis

In dentistry, if a hydrocolloidimpression is left to stand in an environment without sufficient moisture after the impression is taken, the impression will shrink & distort after a period of time. This dimensional change makes the impression, and the resultant model, inaccurate. Hence it needs to be wrapped in damp tissue - OR the impression needs to be poured up in dental plaster immediately.

In medicine this refers to the process of contraction that occurs to a bloodclot. At the start of the clotting process there is a loose network of fibres, mixed in with plasma and blood cells. By this process the split blood vessels are sealed off, and a hard scab formed.